U2270B_08 Datasheet, PDF (13/18 Pages) ATMEL Corporation – Read/Write Base Station

U2270B
4.3 Application 3
This application is comparable to “Application 2” but alters the operating frequency. This allows
higher antenna resonance tolerances and/or higher communication distances. This application
is preferred if the detecting microcontroller is close to the U2270B, as an additional microcontrol-
ler signal controls the adequate operating frequency.
Figure 4-3. Application Circuit 3
4×
1N4148
68 kΩ
75 kΩ
4.7 nF
+
5V
22 µF 47 nF
100 kΩ
1 nF
1.5 mH 82Ω
Antenna
1N4148
180 pF
100Ω
470 kΩ
43 kΩ
V_S V_EXT DV_S V_Batt
RF
MS
COIL2
CFE
U2270B
COIL1
Standby
C_IN
1.5 nF C_HP
Input
HIPASS
DGND
Output
OE
GND
BC846
4.7 kΩ
1.5 kΩ
V_DD
Micro-
controller
V_SS
GND
Note:
Application examples have not been examined for series production or reliability, and no worst
case scenarios have been developed. Customers who adapt any of these proposals must carry
out their own testing and be convinced that no negative consequences arise from the proposals.
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4684E–RFID–02/08